I edited /public/includes/Glossary_Genesis.php from line 41 to line 60 this way:
if ( is_singular() || genesis_get_option( 'content_archive' ) ==="full") {
$content = get_the_content( get_the_ID() );
if ( is_single() && 'open' === get_option( 'default_ping_status' ) && post_type_supports( get_post_type(), 'trackbacks' ) ) {
echo '<!--';
trackback_rdf();
echo '-->' . "\n";
}
if ( is_page() && apply_filters( 'genesis_edit_post_link', true ) ) {
edit_post_link( __( '(Edit)', 'genesis' ), '', '' );
}
} else if ( 'excerpts' === genesis_get_option( 'content_archive' ) ) {
$content = get_the_excerpt( get_the_ID() );
}
/*
if ( is_archive() ) {
if ( genesis_get_option( 'content_archive_limit' ) ) {
$content = get_the_content_limit( ( int ) genesis_get_option( 'content_archive_limit' ), genesis_a11y_more_link( __( '[Read more...]', 'genesis' ) ) );
} else {
$content .= genesis_a11y_more_link( __( '[Read more...]', 'genesis' ) );
}
}
*/
in particular, line 41 becomes:
if ( is_singular() || genesis_get_option( 'content_archive' ) ==="full") {
and the lines from 54 to 60 are commented, since Genesis takes already care to add the “[read more]” link.
This solves the problem.
However, some shortcodes and twitter cards are not rendered.